Lubricants



tion. This saponification may Patented Feb. 12, 1946 a LUBRICANTS U Wilfred Gallay and Ira E. Puddington. Ottawa...

' f ntario, Cana da,1assignors, bymesne asilignments, to Standard Oil Development Company, v Linden, N. J a corporationoi Delaware NoDrawing."Application oamm, 1942, i 4 :Serial No.4.63,180- I I This invention .rel ates to novel 'lubricatins greases and'methods of manui'acturing same, and

it also relates to novel intermediate products useful forot l 1erpurposes. v v i Heretofore soda base greases haveb'een made by cooking up a fat or fatty acid in a mineral 'oil,

and reacting the "mixture with aqueous alkali While heating to 100? C. or higher emu saponification is completed, which is followed generally by additional cooking to cause evaporation oi the resultant water or glycerine'; this process requires alarge'amountoi time and is not as foolproof as might be desired. Various eflorts have been made to'improve one or another phase or this grease '3 manufacturing process, but none'has proved entirely satisfactory, either because the new step is too expensive or too time-consuming, or it is not subject to sufflciently accurate control for the preparation or lubricating 'grea'ses having a uni-' form grease structurajwhich, asjis well-known, is a very sensitive andelusive characteristic.

The primary object oithe present invention is to solve the problems of the prior art by providing a method which is quick, economical, simple .in its operation, efficient, and conducive to uniform results. These and other obiectsand I advantages 'of the invention will appear more fully from the following description. a

'I'he invention comprises suspending an alkali such as caustic sodaginzfiakeaor other suitable form, or othersaponiiying agents as will be discussed later, in a non-reactiveliquid medium, for

example a portion oimineral oilandmechani cally comminuting said alkali while dispersed in the oil until a predominant portion of the particles of alkali is at'leastas low as 5/1.,11516; and thenusing the resultant very active alkali-oil dispersion iorxsaponiifying, i. *e. substantially. neutralizing, a fat or. fatty acid,- adding sufllcient' oil 1 to make 'a grease-oi the requiredjtexture, and using enough heat to eijiectcomplete saponiflcacarried out in various ways.

In making the alkali-oil mast t is best'to put the oil '(or other non-reactive liquid medium), in a ball mill or other suitable mill, and

then add anhydrous caustic soda in flake, stick;

or other form' andproceedwith themillingxuntil the alkali, has been reduced to the'de'sired degree" oi fineness so that it'will stay in "suspension in the oil. This mechanical comn'iinution. of the alkali produces particles of an extremely fine state or subdivision, such as mostly lessthan 5 and preferably less than l in diameter. In'ia'ct, microsopic examination indicates that a number of particles in the resultant dispersion have dimensions' approaching that or colloids. 'I he time (class-411 7 required in'a ball-mill win, of course,.depend upon Q a 'number of factors.- such as the type. diameter and speed of rotation-oi the mill as well 'as the number and,size o1 the-balls (which may be of steel, stainlesssteeLfiint pebbles orIother suitable material) "and theamount and viscosity of the alkali-oil charge. Normally, however, a milling time rzingingirom-about 2 hours to "about. 18 hours is sufficient. With a ball-mill or pebble mill the best loadingis practically haltiull of "balls and liquid J t covering the'balls. 'I'his givesthemost eflicientgrinding-action.

1 If desired, the mechanical comminution of the ingthe; crudesuspension through a colloid mill, one or. more times, 7 depending. upon the original .size of the alkali particles, the rotation speed or a the colloid mill, the aperturesetting'oi the discs or.- other adjusting means or the colloid mill, as well as the proportion and viscosity of the mineral oil vehicle. Chaser mills, pan mills, rod mills,

i mulling mills, disc mills and others could be used.

9m alkali to be usedin preparing'theaikali dis- I persion may be the ordinary alkali oi" commerce 26 which usually contains lessthan 2% or water,

and maybesubstantially anhydrous. H a

.Whenthe particles .of alkali such" as anhy- ,drous caustic soda are 'thusiinely divided in the presence of; the mineral oil serving both as'a fluid 30. suspending medium or vehicle as well as protect- ,ing the alkali'irom contact with moisture of the air, etc), the resultant dispersion is uniform'both in qualityand in concentration of alkali in the 011,. andis substantially stable against settling, a5-particularlyfif a smallfamount'or a protective agent is added prior or subsequentlyto milling,

preferably priorto milling; and this is a great 7 advantage from a practicaland commercialpoint of view asit enables the production ot'lub'ricat- 40 ing greases of uniform quality and makes that possible with relatively simple fool-prootopera tions- If desired, instead or using'the'alkali oil dispersion directly" in the iorm in whichitissues from the ball-mill, orrthe colloid mill if'such is .useci, the procedure may be modified asi'or instance by first subjecting-the suspension of alkali fiakes in oil to vball-milling to eflect a substantial' reduction in alkali particlesize, and then further reducing the alkali particle size bypassthe first crude di'spersion through a colloid v mill with'relatively fine setting of the discs. or

other adjusting means.-

, =As still another odlficatiim of the invention, thejdispersion resulting from the passage of the flake alkali-oil suspension through either a'ballmill or a colloid mill may'be fractionated in order to separately recover the ultra fine particles.

. alkali particles in the oil may be ,e'fl ected by pass- I This may be accomplished by diluting the'crude dispersion (comingfrom the ball-mill or colloid mill), with a substantial amount, e. g., 10% to 500% by volume, of an inert volatile diluent such as petroleum, naphtha, or a liquefied gaseous hydrocarbon such as pentane, butane, or .propane, in' the presence of which diluent only fats, such as mutton tallow, beef stearin and the like, or various fatty acids, such as stearic acid, oleic acid or other high molecular weight fatty acids, such as fatty acids derived from fatty oils, such as cottonseed oil and the like, or synthetic fatty acids obtained by the oxidation of high molecular weight or substantially saturated hydro- I carbons, such as paraflin wax, or naphthenic tion of the total suspension could be made initially 1 in an inert volatile diluent as mentioned, leavingouttheoil. I

Inusing the abovedescrib'ed alkali-oildispersions for the preparation of lubricating greases, it is preferred to cause a saponiflcation of the fatty material, such as a fat or fatty acid, directly in situ and this is preferably accomplished by first dissolving the fator fatty acid in the proper amount of the desired type of mineral oil and then adding the alkali-oil dispersion thereto with agitation to obtain prompt and em cient mixing, and heating the resultant mixture to a saponiflcation temperature which mayrange from room temperature, in the case of the most active materials, to slightly elevatedtemperatures', suchas 140 F., 180 F., 210 F., or so. The saponiflcation reaction yields glycerol with fats and water with fatty acids. The amount of water so formed is relatively so small that its removal is not required and therefore high temperatures to get rid of water are not required. Due to the 'great reactivity v of the fine dispersion of the alkali in oil, saponification temperatures very much lower than used heretofore may be used satisfactorily. The resultant grease may, of course, be subjected to further cooking in order to evapcrate moisture or to distill off glycerine resultingfrom the saponlfication reaction. The mineral oil to be used incarrying out the present invention, insofar as the alkali-oil dispersion is concerned, may be any type of refined mineral lubricating oil having a Saybolt viscosity at 100 F. between theapproximate limits. of .100 seconds and .5000 seconds) and preferably between the somewhat narrower range of 100 seconds and 900 seconds. It is to be understood that these are the common practical limits for the petroleum products to be used as the alkali carrying media, but lighterlfra'ctions such as fuel oil, naphthas and more'volatile products may be used. The oil may be obtained from any of the commonly or mixed base crude petroleum oils, and the oil used may have been recovered from crude petroleum by any of, the commonly'used' refining a methods, such asdistillation, fractionation, solbe any of the above types of oil and may have any desired viscosity or boiling range as commonly used for :the preparation. of lubricating greases.

The fatty material to be subjected to saponification may be any of the commonly available acids, etc., or mixtures of these or other equivalent acids, including the whole range of fatty acids, for example stearic, butyric and acetic and mixtures of such acids.

The process of the present invention may be carried out by batch operation or continuously, to which it is adapted very satisfactorily by continuously mixing together a solution of saponifiable material in oil and active mechanicallycomminuted alkali-oil dispersion, both of which may have beenpreheated if, and to such extent as, necessary for saponification in situ, with or without further continuous heating asby passage of the mixture through a heated pipe coil for a sufficient time to insure completion of the saponification reaction.

In preparing lubricating greases as above described, as an optional addition agent a small amount of materials such as sodium stearate, sodium oleatejstearic acid, oleic acid, or other similar soaps or fatty acids, etc., may be added to the alkali-oil mixture to give additional protective action during passage through the colavailable crudes such as parafiinic, naphthenic loid mill or during the ball-milling operation, said protective action being against coagulation or agglomeration ofthe finely divided alkali.

Although in the above discussion caustic soda is the only alkali specifically mentioned, it should be understood that other .alkalies may be used; for instance, lithium hydroxide and caustic potash may be used, or mixtures of these several alkali. Lithium hydroxide gives a water. resistant grease which resists high temperatures. The

.amount of lithium soap required to give a good grease is relatively small. Furthermore although the invention is considered especially applicable to the alkali soap greases, calcium hydroxide, magnesium hydroxide, barium hydroxide, lead oxide (PbO), nickel oxide, cobalt oxide, manganese oxide (MnO) and others can also be used for grease manufacture according to this invention, The concentration of the alkali-oil suspension to be subjected to the mechanical combination may range between the approximate limits of 10% and 50% by weight, or preferably between the narrower limits of about 20% to 40% by weight, depending upon other factors such as the viscosity of the mineral oil vehicle, the mechanical power available, etc.

Lubricating greases made according to the present invention are generally short flbered in texture and excellent and uniform in quality. The yield obtained varies to a substantial extent with :the type of saponifiable material used; for instance, with the same dispersion of caustic soda in oil, stearic acid gave a high yield, oleic acid a low yield, and mutton tallow an intermediate yield (a high yield means a low soap content for a grease of any particular penetration). Microscopic examination. of the grease made with the stearic acid just referred to, showed that this I grease contained a major proportion of very small soap crystals, whereas-the similar grease made with oleic acid (which gave a low yield) contained a major proportion of relatively large agglomerates ,oi and'a similar made from mutton tallow contained a largenumber of both fine soap crystals agglon'ier ate'sotsoapcrystals. l I

n It has also been found that ii the short ,flbered sre'aselproduced as above describedis Put thro h a colloid mill, the .textureis changedwith there's suiting formation of a flber grease.' :1t I

seconds but a 95 viscosity index in Ex ample manda steam-refined cylinder stock having' a*-viscosity of about 190' seconds at'210, F.

in-Example 3'. The temperatures to which these mixtures" were heated were.176: F. for Examples 3 showed the following-results also" be noted that made according to this invention maybeheatedupto temperatures as high as 300". 1*. withoutv makingvany apparentchange in the grease structure but heatv A solution was made, .at room tempera ture, of oieic" acid in, anacid *and' clay-treated Co1 ombi'an;disti1late"having' a viscosity of about mg aboveeoo F. eflots substantial f mo t 500 seconds Saybolt at ioo 'r'; and a viscosity in. recrystallization. dex of 40, and some ofthevsame caustic-oil dis- Altho ugh one obvou's advantage of this invene i made ln li lxample 1 was added to the tion is' thereactivity of; the alkalis sp n a i 1 oleic' acid solutiontand the mixture was heated to consequent rapid saponiiication even. at, room or, about 14051. until saponiflcation was complete. r lat e j c praturesaanother important 'Thel-resultinggreasewas averysatisfactory prodadvantage is that the-Jfl'nai Pro ct c nt ins n uct,although' the yield obtained was considerably soap-coated alkaliparticlesas sometimes occurs lower thanithatobta ined in vthe Examples 1.2, when larger particlesofalkali are used. A'further a di ai I 1 advantage is the substantial absence of water in o l1 ff Examples 50nd 6. the alkali "suspensiomia'hd therefore excessives mfl 'f f s'w y heating is not required after saponiflcation. ton n m mineral at and adding Having thus described the inventmnsome of the sodium hydroxide dispersion made in Y pellmental. data are given 1 the sake Example 1, the reaction being completed at a illustration but without the intention of limiting temperature of to 1 0 E Different propel; the invention to the specific examples e tions of mutton tallow and different oils were Example 1 used as indicatedin the following table which I also shows the penetration data on the resulting 10 parts by weight of stearic acid were dis-, I gummy n the percent m thereim Formula Unworked pen. Worked pen. gf fii 5.. 10% mutton tallow soaps in 900v ity oil (acid 194 at F... 305at 78 F... 0.22 and clay-treated Colombian distillate).

6 20% mutton tallow soap: in 500 viscosity oil (acid 88 at 76 F.... 213 at 79 F... 0.5

and clay treated Colombian distillate).

solved at about 120* F. m 90'parts by weight or a a mineral oil having the following inspection:

Viscosity (Saybolt)- seconds at F.

Viscosity (Saybolt) seconds at 210 F-. 55.8 Viscosity index 47 A. P. I. gravity 23.2 Flash F-- 40o Robinson, color 9% Neutralization No 0 .50 Pour point 15 F.

35 parts by weight'of anhydrous flake. caustic soda were dispersed in '65 parts by weight or the same mineral oil at about 70 F. by ball-milling- 18 hours in a one gallon capacity porcelain bailmill having flint pebbles about1.5'inches (about 4 cm.) diameter, the mill being about /3 filled with the balls. A total or 800 gms. 01' the alkali oil suspension was used.,The resultant causticoil dispersion was added to the acid-oil solution and the mixture heated to about F. at which temperature saponificati'on proceeded virtually" instantaneously, the viscosity had very substantially increased and the saponiflcation was complete. The manufacture of plate.

Examples 2 and 3 The procedure used in-Example .1 was repeated with two diiferent oils, using an oil having a 500.

- 'ing in situ with the caustic-oil dispersion used.

the grease was com 'lheresulting greases were very smooth and short iibered. Photo-micrographic examination show that the structure of grease #5 (made with a 10% tallow in the refined Colombian oil) might be consldered as acomposite or mixture of a grease having the extremely fine particles as obtained in Examples 1, 2 and 3 with stearic acid, and a grease having larger soap particles or'agglomerates as produced in Example 4 with oleic I acid.

Example Greases'prepared in a manner similar to that described above in Example l6' were passed through'acolloid mill, and in all cases fiber greases were obtained, the length of texture de- 7 creasing with increasing V. I. of the oil and in-' 66, creasing with the degree of unsaturation of the soap. a

7 'lia'am plet 7 Using 10% of cottonseed fatty acids, saponify in Example 1,*and passing the resulting grease through a colloid mill produced a very fibrous grease.

Example 9 In order study the effect of further. heating, some of the greases prepared as above described to atemperature of 300 were heatedin a grease kettle with stirring. samples being .examined microscopically during the heating period; By using rate in a 500 viscosity ,paleoil. it was found that there was noappreciable change up to 300 1". When this grease was allowed to c001, thQconsistency showed a marked decrease a compared with before heating, a microscopic examination indicating that the crystalshad grown both in length and in cross-section, thus the reheating I". brought about a partial recrystallization oi the soap. 'ihus it may be a stated that heating the grease to- 300 I. does not produce any large eiiect on' the texture and con I sistencyoi the grease. v a

It is not intended that this inventionbe limited to any of the examples which have been mentioned merely for the sake of illustration but only by the appended claims in which it is intended to claim all novelty inherent in the invention; as well as equivalents falling. within and spirit oi the invention.

Weclaim: v

1. Theprocess oi'making greases which comprises dissolving a saponiflable. compoundin' a portion of mineral oiLdlspersing a saponitying agent in a non-reactive liquid vehicle; mechanically comminuting said saponifying agent. while dispersed in said vehicle until the particle size or said saponliying agent is predominantly at least 30 as low as 5;, and mixing said solution of upon!- the scope portion of "3. Proces according aaoaaov iiable compound and said saponiiying agent dispersion to produce a saponiflcation reaction.

- .2. The process of making greasesfwhich'comprises dissolving, a saponifiable. compound ina mineral oil, dispersinganalkali in a non-reactive liquid vehicle, mechanically milling said'alkali while dispersed in' said vehicle until the particle size of said alkali is predominantly at least as :low a .51, and mixing said solution oi saponifiable compound and said alkali dispersion to produce a saponificationreaction.

to claim 2 in which the mechanical comminution oi the alkali is eflected by colloid milling.

4. Process according to claim 2 in which the alkali dispersion is made by ball-milling and the resultant grease is put througha colloid mill to make a fiber grease.

p 5. The process of making. lubricating greases which comprises dissolving a high molecular weightfiatty acid in a mineral oil, suspending flake caustic soda in a mineral oil'to obtain a mixture containing 20-40% by weight of caustic, mechanically milling, this suspension until the caustic particle size is at least as small as 1;, adding the resulting dispersion to the oil solution I of the fatty acid, heating the mixture to a temperature of to F; until the saponiflcation is complete.

V WIIJ'RED GAILAY.

IRA E. PUDDINGTON. 

